Optical telecommunications networks are growing increasingly complex, developing beyond simple passive transport of signals to dynamic routing of the signals. A main objective of power management in these dynamic networks, for example metropolitan area networks (MANs), is the management of network power levels during adding and dropping of channels, network upgrades and reconfigurations. Several methods of such power monitoring and management in optical networks are currently available.
The U.S. Pat. No. 6,304,347 to Beine et al. issued Oct. 16, 2001 and entitled “Optical power management in an optical network”, discloses a method of managing power levels in a network by providing the nodes of the network with configurable parameters at each node. The input powers to each node are maintained at a constant level by adjustment of the node configuration parameters. Thus, this patent provides management of network power by strictly maintaining constant power levels at specific points in the network, preventing the network from adapting to changing conditions such as component degradation.
The U.S. Published Patent Application No. 20030053163 to Li et al. dated Mar. 20, 2003 and entitled “Analogous channel method for performance monitoring and equalization in optical networks”, discloses a method of monitoring and equalizing dense wavelength division multiplexing (DWDM) optical links by adjusting input power.
The U.S. Pat. No. 6,400,479 to Zhou et al. issued Jun. 4, 2002 and entitled “Optical Power Balancer for Optical Amplified WDM Networks”, discloses a method of managing power levels in a network by adjusting transmitted signal powers to achieve a desired optical signal-to-noise ratio.
The U.S. Pat. No. 6,040,933 to Khaleghi et al. issued Mar. 21, 2000 and entitled “Method and apparatus for channel equalization in wavelength division multiplexed systems”, discloses a method of equalizing channel powers by adjusting transmitted signal powers so that a first channel power is equal to a second channel power at a predetermined location in the optical network.
The U.S. Published Patent Application No. 20030035170 to DeGrange et al. dated Feb. 20, 2003 and entitled “Method and System for Coordinating and Utilizing Channel Power Information in an Optical Communications Network”, discloses a method of coordinating channel powers information and determining weighting values for each channel in order to control channel launch powers, and a system for controlling channel launch powers based on these weighting values.
The U.S. Published Patent Application No. 20020101637 to Khaleghi et al. issued Aug. 1, 2002 and entitled “Method for Channel Balance”, discloses a method of balancing channel powers by calculating the required transmitter power change to optimize such network parameters as Optical Signal To Noise Ratio (OSNR), Bit Error Rate (BER), channel power, and power spectral shape.
The last five patent documents provide power management only through control of transmitted or input power, limiting the degree to which the network can compensate for power level fluctuations.
The U.S. Published Patent Application No. 20030133713 to Ng et al. filed Jul. 17, 2003 and entitled “Method and System for Multi-Level Power Management in an Pptical Network”, discloses a method and system of managing power levels in a network through equalization of channel powers at specific points in the network. This patent application restricts the operation of the network to the extent of maintaining equalized power between channels, between bands, and between fibers, leaving other global network operating parameters such as OSNR or BER outside of the scope of this application.
Therefore, there is a need in industry for the development of an improved method for comprehensive and dynamic power management in an optical network.